Search

Nanoparticle assemblies can be investigated in 3 dimensions using electron tomography. However, it is not straightforward to obtain quantitative information such as the number of particles or their relative position. This becomes particularly difficult when the number of particles increases. We propose a novel approach in which prior information on the shape of the individual particles is exploited. It improves the quality of the reconstruction of these complex assemblies significantly. Moreover, this quantitative Sparse Sphere Reconstruction approach yields directly the number of particles and their position as an output of the reconstruction technique, enabling a detailed 3D analysis of assemblies with as many as 10 000 particles. The approach can also be used to reconstruct objects based on a very limited number of projections, which opens up possibilities to investigate beam sensitive assemblies where previous reconstructions with the available electron tomography techniques failed.

The light harvesting capacity of plasmonic nanoparticles is a fundamental feature for catalysing chemical reactions close to their surface. The efficiency of the photochemical processes depends not only on the geometrical aspects on a single particle level but also on the complexity of the multiparticle architectures. Although, the effect of the particle geometry is progressively understood in the relevant photochemical processes (water splitting and hydrogen evolution), there are experimental and theoretical needs for understanding the role of the shape in the multiparticle systems in the photocatalytic processes. Here we have shown that macroscopic plasmonic substrates comprising gold nanostars exhibit better efficiencies than nanorods or cubes in the photoregeneration of cofactor molecules. We performed photochemical and photoelectrochemical measurements, supported by theoretical simulations, showing that the unique geometry of nanostars – radially distributed spikes – contributes to stronger light absorption by the plasmonic film containing that type of nanoparticles.

We report a generic method for the preparation of polymer-coated plasmonic nanostructures with tunable thickness of the hydrophobic polymer spacer. By simply changing the order of addition of a block copolymer and water, encapsulation of either individual or assembled nanoparticles within copolymer micelles can be selected, thus providing wide versatility to the method.